This application claims the benefit of Korean Patent Application No. 1999-52109, filed on Nov. 23, 1999, and the benefit of Korean Patent Application NO. 2000-59958, field on Oct. 12, 2000, under 35 U.S.C. xc2xa7119, the entirety of which is hereby incorporated by reference.
1. Field of the invention
The present invention relates to a glare shielding device of a welding helmet and a method of controlling the same.
2. Description of Related Art
In recent, glare shielding devices are widely used in the welding and cutting torch technology in order to protect eyes of workers. With such glare shielding devices the radiation above 780 nm (infrared) and below 365 nm (ultraviolet) are filtered and only the radiation in the visible range is dimmed, so that workers can discriminate a welding position of a specific spot.
U.S. Pat. No. 5,315,099 (German Patent No. 2,606,416) discloses a glare shielding device which includes an electro-optical glare shield having at least one liquid crystal cell; an electronic circuit connected to the electro-optical glare shield for applying an electric operating voltage thereto for varying an optical transmission value of the at least one liquid crystal cell; and a light sensor connected to the electronic circuit for providing an input signal thereto indicative of sensed light adjacent to the electro-optical glare shielding device.
U.S. Pat. No. 5,444,232 (European Patent No. 630,627) discloses an antiglare device which includes a protective light filter, a photosensor detector electronics adapted to produce a dimming signal, evaluating electronics which control an electro-optical protective light filter, a controller to control the brightening time of the protective light filter, the controller detecting at least the intensity of the light impinging on the sensor; the controller being objectively connected to a timing generator to detect at least the duration of the dimming signal produced by the detector electronics; and the controller including means to interlink the acquired data with respect to logic and/or time.
The antiglare device disclosed in U.S. Pat. No. 5,444,232 detects the absolute light intensity, the respective amount of light and the welding duration, and interconnects these parameters in a meaningful manner with respect to logic and/or time by means of suitable electronics, thereby optimizing the brightening time to the given circumstances.
Such a glare shielding device has an advantage that a circuit construction is simple. However, it has the following disadvantages. Firstly, a time delay occurs between an input of welding light and an operation of the antiglare device. Secondly, power consumption is high due to an operation of a control circuit having a microcomputer for continuously detecting a variation of an input welding light. Thirdly, in case of the device providing an automatic turn off function in order to prevent a continuous power consumption, a switch should be turned on by a manual actuation in order to operate the device again. This is a troublesome task. Fourthly, a photosensitivity of the input welding light should be controlled depending on a welding condition. Fifthly, in case that a welding signal is detected using only a light signal, since detected signals depend on a welding method and a welding machine, the glare shielding device may abnormally operate.
In order to overcome the problems described above, a glare shielding device using a non-optical detection means has been introduced. In this case, since a continuous light shielding phenomenon may occur due to a non-intended abnormal operation that may be generated by a latent magnetic filed in surroundings, workers can not discriminate welding light due to the continuous light shielding phenomenon, whereupon workers can not check a welding state. For example, a spark during a welding process may generate a magnetic field.
For the forgoing reasons, there is a need for a glare shielding device that can minimize a power consumption and that worker can check a welding state during a welding process.
To overcome the problems described above, preferred embodiments of the present invention provide a glare shielding device that can minimize a power consumption and that worker can check a welding state during a welding process.
In order to achieve the above object, the preferred embodiments of the present invention provide a glare shielding device for a welding helmet having a liquid crystal panel. A solar battery circuit converts light into an electrical energy to output first and second output voltages. A charging circuit charges the first output voltage to provide a driving voltage. An oscillator circuit generates an oscillating signal in response to the second output voltage. A high-voltage amplifier charges-pumps the driving voltage in response to the oscillator circuit to generate a high voltage. A regulator regulates the high voltage to generate a stable driving voltage. An activation voltage generator generates a liquid crystal activation voltage in response to the oscillating signal. A driving circuit power controller generates a ground voltage by being switched from a standby mode to a driving mode in response to a light detection signal, and maintains a floating state by being switched from the driving mode to the standby mode in response to a power off controlling signal. A light detector detects a welding light using the second output voltage as a power source, and outputs the light detection signal using the driving voltage as a power source. A high-frequency detector detects a high-frequency generated during a welding process using the light detection signal as a power source, and outputs a high-frequency detection signal using the liquid crystal driving control signal as a power source. A liquid crystal activating portion activats the liquid crystal panel using a minus voltage between the high voltage and the liquid crystal activation voltage in response to the light detection signal, and maintains an activation action during a predetermined period in response to the activation controlling signal. A liquid crystal driving portion drives the liquid crystal panel using a minus voltage between the liquid crystal driving voltage and a ground voltage in response to the oscillator circuit. A controller works in response to the light detection signal, generates the activation controlling signalduring an initial activation time in response to the high-frequency detection signal, generates the driving control signalafter the initial activation time passes, stops generating the driving control signal and generating the power off control signal and performs the standby mode when the light detection signal and the high-frequency detection signal does not exist.
The charging circuit includes a charging battery for charging the first output voltage; a plurality of light emitting diodes for being connected both terminals of the charging battery and preventing an overcharge; and a smooth capacitor for smootting an output voltage of the battery to output the driving voltage. The regulator includes an adjusting means for adjusting a level of the liquid crystal driving voltage to adjust a light transmittance of the liquid crystal. The glare shielding device further includes a temperature detector for detecting a temperature of the liquid crystal panel, wherein the activation voltage generator adjusts a level of the liquid crystal activation voltage in response to a temperature control signal and outputs it, and the controller outputs the temperature control signal in response to a temperature detection of the temperature detector.
The preferred embodiment of the present invention further provides a method of controlling a glare shielding device for a welding helmet. The method includes, in a standby mode, generating first and second output voltages by converting ambient light into an electrical energy using a solar battery, generating a driving voltage of a predetermined level by charging the first output voltage, generating a high voltage and an activation voltage by charge-pumping the driving voltage in response to the second output voltage, and for maintaing a liquid crystal activating portion and a liquid crystal driving portion to be in a floating state; detecting a welding light; switching the liquid crystal activating portion and the liquid crystal driving portion to a driving mode by releasing the floating state, and activating a liquid crystal panel through the liquid crystal activating portion using a minus voltage between the high voltage and the activation voltage; detecting a high frequency generated during a welding process; driving the liquid crystal panel through the liquid crystal driving portion by finishing an activation time of the liquid crystal activating portion when the high frequency; and switching the liquid crystal activating portion and the liquid crystal driving portion to the standby mode when the high frequency and the welding light are not detected.
At this point, a level of the activation voltage varies according to an ambient temperature of the liquid crystal panel to rapidly activate the liquid crystal panel.
The preferred embodiment of the present invention provides a glare shielding device for a welding helmet. The glare shielding device includes a liquid crystal panel. A solar battery circuit converts light into an electrical energy to output first and second output voltages. A charging circuit charges the first output voltage to provide a driving voltage. An oscillator circuit generates an oscillating signal in response to the second output voltage. A high-voltage amplifier charge-pumps the driving voltage in response to the oscillator circuit to generate a high voltage. A delay time setting portion sets an off time of the liquid crystal display panel. A reset circuit generates a reset signal by a switching of a reset switc. A regulator regulates the high voltage to generate a stable driving voltage. An activation voltage generator generates a liquid crystal activation voltage in response to the oscillating signal. A driving circuit power controller generates a ground voltage by being switched from a standby mode to a driving mode in response to a light detection signal, and maintains a floating state by being switched from the driving mode to the standby mode in response to a power off controlling signal. A light detector detects a welding light using the second output voltage as a power source, and outputs the light detection signal using the driving voltage as a power source. A high-frequency detector detects a high-frequency generated during a welding process using the light detection signal as a power source, and outputs a high-frequency detection signal using the liquid crystal driving control signal as a power source. A liquid crystal activating portion activats the liquid crystal panel using a minus voltage between the high voltage and the liquid crystal activation voltage in response to the light detection signal, and maintains an activation action during a predetermined period in response to the activation controlling signal. A liquid crystal driving portion drives the liquid crystal panel using a minus voltage between the liquid crystal driving voltage and a ground voltage in response to the oscillator circuit. A controller is reset in response to the reset signal and performing a self-test mode, works in response to the light detection signal, generates the activation controlling signalduring an initial activation time in response to the high-frequency detection signal, generates the driving control signal after the initial activation time passes, stops generating the driving control signal and generates the power off control signal, and performs the standby mode when the light detection signal and the high-frequency detection signal does not exist.
Using the glare shielding device according to the preferred embodiment of the present invention, a power consumption can be minimized and worker can check a welding state during a welding process. Further, since by detecting an ambient temperature and compensating an activation voltage in light that response characteristics is lowered at a low temperature, an initial glare shielding effect can be improved.